Using Uuids To Assemble Or Activate File System Devices; Finding The Uuid For A File System Device; Using Uuids In The Boot Loader And /Etc/Fstab File (X86) - Novell LINUX ENTERPRISE SERVER 10 - STORAGE ADMINISTRATION GUIDE FOR EVMS Administration Manual

3.2.1 Using UUIDs to Assemble or Activate File System
Devices
The UUID is always unique to the partition and does not depend on the order in which it appears or
where it is mounted. With certain SAN devices attached to the server, the system partitions are
renamed and moved to be the last device. For example, if root (/) is assigned to /dev/sda1
during the install, it might be assigned to /dev/sdg1 after the SAN is connected. One way to
avoid this problem is to use the UUID in the boot loader and /etc/fstab files for the boot
device.
A UUID never changes, no matter where the device is mounted, so it can always be found at boot. In
a boot loader file, you typically specify the location of the device (such as /dev/sda1 or /dev/
evms/sda1) to mount it at system boot. The boot loader can also mount devices by their UUIDs
and administrator-specified volume labels. However, if you use a label and file location, you cannot
change the label name when the partition is mounted.
You can use the UUID as criterion for assembling and activating software RAID devices. When a
RAID is created, the md driver generates a UUID for the device, and stores the value in the md
superblock.

3.2.2 Finding the UUID for a File System Device

You can find the UUID for any block device in the /dev/disk/by-uuid directory. For example,
a UUID looks like this:
e014e482-1c2d-4d09-84ec-61b3aefde77a
3.3 Using UUIDs in the Boot Loader and /etc/
fstab File (x86)
After the install, you can optionally use the following procedure to configure the UUID for the
system device in the boot loader and /etc/fstab files for your x86 system.
1 Install the SUSE
2 After the install, boot the system.
3 Open a terminal console as the root user or equivalent.
4 Navigate to the /dev/disk/by-uuid directory to find the UUID for the device where you
5 Edit /boot/grub/menu.1st file, using the Boot Loader option in YaST2 or using a text
30 SLES 10 Storage Administration Guide for EVMS
®
Linux Enterprise Server for x86 with no SAN devices connected.
installed /boot, /root, and swap.
4a At the terminal console prompt, enter
cd /dev/disk/by-uuid
4b List all partitions by entering
ll
4c Find the UUID, such as
e014e482-1c2d-4d09-84ec-61b3aefde77a —> /dev/sda1
editor.
For example, change
kernel /boot/vmlinuz root=/dev/sda1